Outbreaks of lethal cyanogenic glycosides poisonings of cattle after ingestion of Sorghum ssp. grown under drought conditions in August 2022 in Piedmont (North-Western Italy)

Abstract

The following case report aims to present an outbreak of cattle poisoning recorded in Piedmont (Northwestern Italy) during the summer 2022. In the first half of August several accidents occurred in five different farms located in the provinces of Cuneo, Asti and Biella. The first and most severe outbreak was reported in a grazing field located in Sommariva del Bosco (Cuneo) and involved a herd of Piedmontese heifers which ingested a hybrid cultivar of Sorghum bicolor x S. sudanense resulting in the death of 50 animals. Sixteen additional deaths were recorded in the following days in the remaining four farms. In all the latter cases, poisoned cows had been fed with the widespread weed S. halepense. Interestingly, farmers complained that no such events have ever been recorded in all previous years, feeding cattle with or grazing on sorghum being a common practice. Shortly after exposure, the affected bovines showed recumbency, sialorrhea, tachypnea, air hunger and muscle tremors followed by acute depression and death, pointing thereby to cyanide poisoning. Most of animals received an oral or intravenous treatment with the antidote sodium thiosulfate, albeit this compound is not typically referred to as the sole remedy against cyanide toxicosis. All treated animals showed a complete recovery. Carcasses of dead animals were subjected to necropsy and sorghum samples were collected in each farm/field to determine the content of the cyanogenic glycoside dhurrin by LC-MS/MS. As a result, dhurrin concentrations up to 10,000 mg/kg were detected in four plant samples collected from the respective involved farms. The anamnesis, the rapid onset, the clinical picture, the remarkable efficacy of the antidote and the results from necropsies strongly indicated cyanide intoxication. This diagnosis was further supported by the high dhurrin concentrations measured in most sorghum samples, which are consistent with the extreme drought conditions that affected the area including the mentioned farms. In that area, the Regional Agency for Environmental Protection (ARPA) reported several days with summer tropical diurnal and nocturnal temperatures as never experienced before. Therefore, caution is needed when feeding cattle with green chops or while grazing, with a special care in case of potential drought stress suffered by Sorghum plants.